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The Single UNIX &reg; Specification, Version 2<br>
Copyright &copy; 1997 The Open Group

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<h4><a name = "tag_000_010_653">&nbsp;</a>NAME</h4><blockquote>
wcstoul - convert a wide-character string to an unsigned long
</blockquote><h4><a name = "tag_000_010_654">&nbsp;</a>SYNOPSIS</h4><blockquote>
<pre><code>

#include &lt;<a href="wchar.h.html">wchar.h</a>&gt;

unsigned long int wcstoul(const wchar_t *<i>nptr</i>, wchar_t *<i>*endptr</i>,
     int <i>base</i>);
</code>
</pre>
</blockquote><h4><a name = "tag_000_010_655">&nbsp;</a>DESCRIPTION</h4><blockquote>
The
<i>wcstoul()</i>
function converts the initial portion of the wide-character string
pointed to by
<i>nptr</i>
to
<b>unsigned long int</b>
representation.
First it decomposes the input wide-character string
into three parts: an initial,
possibly empty, sequence of white-space wide-character codes
(as specified by
<i><a href="iswspace.html">iswspace()</a></i>);
a subject sequence interpreted as an integer represented
in some radix determined by the value of
<i>base</i>;
and a final wide-character string of one or more unrecognised wide-character
codes, including the terminating null wide-character code of the input
wide-character string.
Then it attempts to convert the subject sequence to an unsigned integer,
and returns the result.
<p>
If
<i>base</i>
is 0, the expected form of the subject sequence is that of a
decimal constant, octal constant or hexadecimal constant,
any of which may be preceded by a + or - sign.
A decimal constant begins with a non-zero digit, and consists
of a sequence of decimal digits.
An octal constant consists of the prefix
0 optionally followed by a sequence of the digits 0 to 7 only.
A hexadecimal constant consists of the prefix
0x or 0X followed by a sequence of the decimal digits and letters
a (or A) to f (or F) with values 10 to 15 respectively.
<p>
If the value of
<i>base</i>
is between 2 and 36, the expected form of the subject sequence is
a sequence of letters and digits representing an integer with the
radix specified by
<i>base</i>,
optionally preceded by a + or - sign, but not including an
integer suffix.
The letters from a (or A) to z (or Z) inclusive
are ascribed the values 10 to 35; only letters whose ascribed
values are less than that of
<i>base</i>
are permitted.
If the value of
<i>base</i>
is 16, the wide-character codes 0x or 0X
may optionally precede the sequence of letters and digits,
following the sign if present.
<p>
The subject sequence is defined as the longest initial
subsequence of the input wide-character string, starting with the first
wide-character code that is not white space and is of the expected form.
The subject sequence contains no wide-character codes if the input
wide-character string
is empty or consists entirely of white-space wide-character codes,
or if the first wide-character code that is not white space
is other than a sign or a permissible letter or digit.
<p>
If the subject sequence has the expected form and
<i>base</i>
is 0, the sequence of wide-character codes starting with the
first digit
is interpreted as an integer constant.
If the subject sequence has the expected form and the value of
<i>base</i>
is between 2 and 36, it is used as the base for conversion,
ascribing to each letter its value as given above.
If the subject sequence begins with a minus sign, the value
resulting from the conversion is negated.
A pointer to the final wide-character string is
stored in the object pointed to by
<i>endptr</i>,
provided that
<i>endptr</i>
is not a null pointer.
<p>
In other than the POSIX locale, additional implementation-dependent
subject sequence forms may be accepted.
<p>
If the subject sequence is empty or does not have the expected
form, no conversion is performed; the value of
<i>nptr</i>
is stored in the object pointed to by
<i>endptr</i>,
provided that
<i>endptr</i>
is not a null pointer.
<p>
The
<i>wcstoul()</i>
function will not change the setting of 
<b>errno</b>
if successful.
<p>
Because 0 and {ULONG_MAX}
are returned on error and 0 is also a valid return on success,
an application wishing to check for error situations should set
<i>errno</i>
to 0, then call
<i>wcstoul()</i>,
then check
<i>errno</i>.
</blockquote><h4><a name = "tag_000_010_656">&nbsp;</a>RETURN VALUE</h4><blockquote>
Upon successful completion,
<i>wcstoul()</i>
returns the converted value, if any.
If no conversion could be performed, 0 is returned and
<i>errno</i>
may be set to indicate the error.
If the correct value is outside the range of representable values,
{ULONG_MAX} is returned and
<i>errno</i>
is set to [ERANGE] .
</blockquote><h4><a name = "tag_000_010_657">&nbsp;</a>ERRORS</h4><blockquote>
The
<i>wcstoul()</i>
function will fail if:
<dl compact>

<dt>[EINVAL]<dd>
The value of
<i>base</i>
is not supported.

<dt>[ERANGE]<dd>
The value to be returned is not representable.

</dl>
<p>
The
<i>wcstoul()</i>
function may fail if:
<dl compact>

<dt>[EINVAL]<dd>
No conversion could be performed.

</dl>
</blockquote><h4><a name = "tag_000_010_658">&nbsp;</a>EXAMPLES</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_010_659">&nbsp;</a>APPLICATION USAGE</h4><blockquote>
Unlike
<i><a href="wcstod.html">wcstod()</a></i>
and
<i><a href="wcstol.html">wcstol()</a></i>,
<i>wcstoul()</i>
must always return a non-negative number;
so, using the return value of
<i>wcstoul()</i>
for out-of-range numbers with
<i>wcstoul()</i>
could cause more severe problems than just loss of precision
if those numbers can ever be negative.
</blockquote><h4><a name = "tag_000_010_660">&nbsp;</a>FUTURE DIRECTIONS</h4><blockquote>
None.
</blockquote><h4><a name = "tag_000_010_661">&nbsp;</a>SEE ALSO</h4><blockquote>
<i><a href="iswalpha.html">iswalpha()</a></i>,
<i><a href="scanf.html">scanf()</a></i>,
<i><a href="wcstod.html">wcstod()</a></i>,
<i><a href="wcstol.html">wcstol()</a></i>,
<i><a href="wchar.h.html">&lt;wchar.h&gt;</a></i>.
</blockquote><h4>DERIVATION</h4><blockquote>
Derived from the MSE working draft.
</blockquote><hr size=2 noshade>
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Copyright &copy; 1997 The Open Group
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